This is the 18313th most frequent Russian word.
шоколад
Chocolate.
Here, 'шоколад' refers to the food item, specifically in its general edible form.
Я люблю есть шоколад.
I love eating chocolate.
In this context, 'шоколадом' refers to the substance chocolate as a covering or topping.
Этот торт покрыт шоколадом.
This cake is covered with chocolate.
Here, 'шоколад' implies different kinds or types of chocolate as categorized by flavor or composition.